Vortex flowmeters are used in the industrial process control field for measuring a flow rate of a fluid. Vortex flowmeters are typically inserted in a flow pipe or conduit that carries the fluid to be measured. Industry applications include petroleum, chemical, pulp and paper, mining and materials, oil and gas, for example.
The operating principle of a vortex flowmeter is based on a phenomenon of vortex shedding known as the von Karman effect. As fluid passes a shedding bar or “bluff body”, it separates and generates small eddies or vortices that are shed alternately along and behind each side of the bluff body. These vortices cause areas of fluctuating flow and pressure that are detected by a sensor. Various different types of sensors are currently in use for detecting such vortices including force sensors, piezoelectric dynamic pressure sensors, or differential pressure sensors, for example. The frequency of vortex generation is essentially proportional to fluid velocity.
The vortex sensors currently used to sense vortices in vortex flowmeters are generally relatively complex and may require a costly design. Further, such sensors require additional fasteners and a robust seal since the sensor or some other suitable structure, must be inserted into the flow tube in order to interact with the vortices for detection. Accordingly, the process fluid is brought into direct contact with such structure and the process intrusion itself must be sealed carefully in order to ensure that process fluid does not leak.